JPS6019009Y2 - Shell fastening device for vacuum booster - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a shell fastening device for a vacuum booster.

Conventionally, in order to connect a pair of shells constituting the outer shell of a vacuum booster, for example a brake booster, generally, flange portions are formed at the outer peripheral ends of both shells to face each other, and both flanges Both shells were connected and fixed with the outer periphery of the diaphragm being sandwiched between the parts.

Therefore, in this type of brake booster, the diameter of the flange portion is further enlarged than the substantial diameter of the shell, which determines the output, which hinders miniaturization.

In view of these shortcomings, the above-mentioned shortcomings can be improved by adopting the following configuration as a shell fastening device for a new brake booster.

That is, in this shell fastening device, the outer circumferential portion of the diaphragm is fitted into the annular groove formed in the first shell, and the outer circumferential portion of the diaphragm is tightly attached to the inner surface of the annular groove and the inner circumferential surface of the second shell. The second shell is provided with an engaging pawl, the first shell is provided with a notch that allows the engaging pawl to pass therethrough, and an engaging portion that interferes with the engaging pawl. The purpose is to connect the first shell and the second shell by engaging the mating claw and the engaging portion.

It is true that the shell fastening device having such a configuration does not require the formation of a flange portion, so the diameter can be reduced by that amount, and the advantage is that the brake booster can be made more compact.

However, on the other hand, in the former shell fastening device, even if the two shells are connected by the engaging claw and the engaging portion, the diaphragm is narrowed inside the shell in which the engaging claw is provided in advance. The outer periphery of the diaphragm can be retracted and the outer periphery of the diaphragm is brought into contact with the flange portion, and in this state, the flange portion of the other shell is brought into pressure contact with the outer periphery of the diaphragm to engage the engaging claw and the engaging portion. However, in the latter shell fastening device, due to its structure, the outer periphery of the diaphragm cannot be narrowed when the outer periphery of the diaphragm is fitted into the annular groove of the first shell. The engaging claw and the engaging portion must be engaged with each other in the above-mentioned state, and for the purpose of miniaturization, the engaging claw should be provided at a position where it interferes with the outer periphery of the diaphragm fitted into the annular groove. As a result, there is a risk that the outer circumferential portion of the diaphragm and the engaging pawl may interfere and the outer circumferential portion may be damaged.

In view of these drawbacks, the present invention provides a shell fastening device having the latter configuration, by forming an inclined guide surface that expands outward to guide the introduction of the outer circumference of the diaphragm into the engaging pawl. Even if the diaphragm and the outer periphery of the diaphragm interfere with each other, damage to the outer periphery of the diaphragm can be prevented.

The present invention will be described below with reference to the illustrated embodiment. The brake booster 1 includes a first shell 2 as a rear shell and a second shell 3 as a front shell.

The first shell 2 is generally formed into a disk shape, and has an annular groove 5 formed on its outer periphery for engaging the outer periphery of the diaphragm 4 .

On the other hand, the second shell 3 is generally formed into a cylindrical shape with a bottom, and the cylindrical portion on the opening side is provided with a smooth stepped portion 6, as clearly shown in FIG. The inner diameter of the opening is made slightly larger than the inner diameter of the opening.

In addition, as shown in FIG. 2, cutouts 7 are formed at a plurality of equally spaced locations over a required range on the circumferential surface of the opening end of the second shell 3, and on the circumferential surface where the cutouts 7 are not formed. A plurality of engaging pawls 8 are formed by partially bulging out radially inward in the shape of a circular arc.

At this time, the axial distance between the end surface of the notch 7 and the inner end surface of the engaging claw 8 is made to match the thickness of the first shell 2,
In addition, each engaging claw 8 is bulged radially inward with its inner end in the axial direction being deeper and its outer end being shallower. An outwardly expanded inclined guide surface 8a is formed to guide the introduction.

Further, the diameter of the outer circumferential end of the first shell 2 extending in the radial direction is made to match the inner diameter of the large diameter portion outward from the stepped portion 6 formed in the second shell 3, and at the outer circumferential end, A protrusion 9 is formed in the notch 7 to allow relative rotation of the engaging waist leather 1 shell 2 and the second shell 3 at a predetermined angle.

Furthermore, the first shell 2 is attached to the second shell 3 on the outer peripheral part of the first shell 2 with the same circumferential side of the protrusion 9 aligned with the same circumferential side of the notch 7. When fitting the first shell 2 to the second shell 3, an arcuate notch 10 is formed to avoid interference with the engaging claw 8 formed on the second shell 3, and a portion between each of the notches 10 After fitting into the shell 3, when both shells are rotated relatively and the other side of the protrusion 9 in the circumferential direction is brought into contact with the other side of the notch 7 in the circumferential direction, the engaging claw 8
It is formed as a retaining portion 11 that connects the first shell 2 and the second shell 3 by coming into contact with the inner end surface of the first shell 2 and the second shell 3.

Note that the other configurations and operations are the same as those of conventionally known brake boosters, so a description thereof will be omitted.

In order to connect the first shell 2 and second shell 3 having the above configuration, first, the outer circumference of the diaphragm 4 is fitted into the annular groove 5 of the first shell 2, and then the A state in which the same circumferential side of the protruding portion 9 is aligned with the same circumferential side of the notch 7 formed in the second shell 3, that is, the engagement claw between the notch 10 of the first shell and the second shell 3. The first shell 2 is fitted into the second shell 3 with the two shells 8 aligned in the axial direction.

At this time, as is clear from FIG. 3, the engaging claw 8 is provided at a position where it interferes with the outer circumference of the diaphragm 4 fitted in the annular groove 5, and the conventional engaging claw is As shown in A, since the engaging claws were formed simply radially inward, there was a risk that the outer peripheral part of the diaphragm would be damaged by the edge of the engaging claws.However, in the present invention, the inner surface of the engaging claws 8 is A sloped guide surface 8a that expands outward is formed, and this guide surface 8
a is deep on the inner end side in the axial direction, shallow on the outer end side, and bulged inward in the radial direction. When it is bulged in an arc shape as in the example, it takes on the shape of a truncated cone, and when it is bulged into a triangular shape with rounded tip corners, it takes on the shape of a truncated triangular truncated pyramid without a sharp point. Therefore, the outer circumferential portion of the diaphragm 4 is provided with the bulge-shaped guide surface 8.
Since a enters in a wedge shape, it is compressed inward in the radial direction of the first shell 2, and is also pushed outward on both sides in the outer circumferential direction, and is smoothly pressed and deformed along the guide surface 8a, thereby preventing any damage. It is possible to pass through the engaging claw 8 without any problem.

When the protrusion 9 of the first shell 2 comes into contact with the notch 7 of the second shell 3, the other side of the protrusion 9 in the circumferential direction and the other side of the notch 7 in the circumferential direction contact each other. , both shells 2
, 3 relative to each other.

In this state, the first shell 2 is connected to the notch 7 of the second shell 3.
The outer circumferential portion of the diaphragm 4 is held tightly between the inner circumferential surface of the second shell 3 and the inner circumferential surface of the annular groove portion 5 of the first shell 2. It is held in place to keep the area airtight.

In addition, in the illustrated embodiment, as shown in FIG.
Although the rigidity of the engaging claw 8 is increased by making the bundle part a into a flat part 8b along the axial direction, the flat part may be omitted.

Further, only during assembly during manufacturing, the engaging claws 8 can be bulged radially inward after the first shell 2 is fitted into the second shell 3. Of course, the present invention can also be applied to other vacuum boosters, such as clutch boosters.

As described above, in the present invention, the outer circumferential portion of the diaphragm is fitted into the annular groove formed on the outer circumferential edge of the first shell, and the outer circumferential portion of the diaphragm is connected to the inner circumferential surface of the annular groove and the inner circumferential surface of the second shell. A plurality of engaging pawls bulging radially inward on the second shell are engaged with notches that allow the first shell to pass through the engaging pawls in order to tightly hold the second shell. an engaging portion that interferes with the pawl, and the engaging pawl and the notch are aligned to form the first on the inner peripheral surface of the second shell.
The first shell and the second shell can be connected by introducing the outer periphery of the diaphragm fitted into the shell and rotating these shells relative to each other to engage the engaging claw and the engaging portion. As a result, the outer diameter of the device can be significantly reduced compared to conventional ones, allowing the two shells to be connected in a detachable manner, and the engaging pawl has a radius that is deep on the inner end in the axial direction and shallow on the outer end. Since the engagement pawl is bulged inward in the direction and has an outwardly expanded inclined guide surface that guides the introduction of the outer peripheral portion of the diaphragm, the bulge is formed on the inner surface of the second shell. The guide surface having a cone-shaped curved surface enters into the outer circumference of the diaphragm in a wedge shape when the outer circumference of the diaphragm fitted in the first shell is introduced into the inner circumference of the second shell, The outer circumferential portion of the diaphragm can be introduced into the inner circumferential surface of the second shell extremely smoothly while being deformed so as to be compressed inward in the radial direction of the first shell and expanded outwardly on both sides in the outer circumferential direction. The outer periphery is not damaged by the engaging claws, and therefore airtight leakage caused by such damage can be prevented.

In addition, since the pressing deformation action generated on the outer circumference of the diaphragm by this guide surface is locally generated at multiple locations on the outer circumference of the diaphragm, deformation is extremely easily performed, and the fitting approach between the first shell and the second shell is facilitated. At times, the engagement claw of the second shell and the notch of the first shell are maintained in the aligned position without causing any relative rotation between them, and the fitting is performed, thereby allowing the planned connection between the two shells to occur. This has the effect of making it possible to remotely perform fitting and locking operations at accurate positions.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention; Fig. 2 is a longitudinal sectional view taken along the line ■-I in Fig. 2; Fig. 2 is a right side view of Fig. 1; and Fig. 3 shows the main parts of Fig. 1. It is an enlarged sectional view. 1... Brake booster, 2... First
Shell, 3... Second shell, 4... Diaphragm, 5... Annular groove, 8...
Engagement claw, 8a...Guide surface, 10...Notch, 11...Engagement portion.

Claims (1)

[Scope of utility model registration request] The outer periphery of the diaphragm is fitted into the annular groove formed on the outer periphery of the first shell, and the outer periphery of the diaphragm is held in close contact with the inner surface of the annular groove and the inner periphery of the second shell. In order to achieve this, the second shell has a plurality of engaging claws bulging inward in the radial direction thereof, and the first shell has a notch that allows the engaging claws to pass therethrough and a retainer that interferes with the engaging claws. and the engaging pawl and the notch are aligned to introduce the outer peripheral part of the diaphragm fitted into the first shell into the inner peripheral surface of the second shell, and both shells The first shell and the second shell can be connected by relatively rotating the engaging pawl and the retaining part, and the engaging pawl is moved deeply outward on the axially inner end side. A vacuum booster characterized in that the end side is shallowly bulged inward in the radial direction, and the engaging claw is formed with an outwardly expanding inclined guide surface that guides the introduction of the outer peripheral part of the diaphragm. Shell fastening device.